Not that I agree with it, but people say this about Chicago too (that it can't support two teams).

It's different though. San Fran and Chicago have nearly identical population densities, but outside San Fran (which is three times smaller) those numbers drop precipitously. And, let's face it, if you live in San Fran, you aren't an A's fan. I honestly think it would work more fairly if the teams were in Oakland and San Jose. Having one team be the team of San Francisco really limits the remaining market. People living in Oakland or San Jose are not traveling to the other city consistently for baseball. If you have the teams there, the San Fran market would then be split north and south.

I know that's never going to happen because realistically San Fran is the big city. But that's why two teams won't work.